Current efforts emphasize the biology and pathogenicity of Mycoplasma species of humans and, where important, how mycoplasmas (or other mollicutes) from animals and other hosts play a role in human or other host infections. Further observations have been made on the role of mycoplasmal infections in immunocompromised patients, usually involving individuals with genetic immune deficiencies, or those patients who are receiving various immunosuppressive drugs because of organ/tissue transplants or treatment of malignant disease. We have now additional evidence of the important role that mycoplasmas of animal origin can play in such infections. Mycoplasma maculosum, an organism commonly found in the canine respiratory and genital tracts, was identified as the causative agent of meningitis in a child with hypogammaglobulinemia. Chemotherapeutic efforts, in the absence of the patient's ability to mount some type of an immune response, have been unsuccessful. These findings, and our previous identification of other feline or canine mycoplasma infections in immunocompromised patients, emphasize why all patients with such immune deficiencies should avoid close animal contacts. Mycoplasmas also play an important role in respiratory disease in man and animals. We have recently identified two new, and previously unreported, Mycoplasma species from microbial agents isolated from the respiratory tract of both desert and gopher tortoises in a collaborative study in Florida and California. The taxonomic characterization of these new organisms has allowed development of a variety of serologic and molecular techniques to rapidly identify the organisms and to study acquisition of infection, disease distribution, immunological responses, and other epidemiological features of a disease in an endangered species. Also, efforts have continued to record the extent and range of the pathogenicity for man of mycoplasma hominis, an organism that normally occurs in the human oral and urogenital tissues. The organism was identified recently in our laboratory from specimens obtained from a post-partum patient with an unusual brain abscess, suggesting a seeding of the organism through the circulation during normal parturition. Since many mycoplasmas or other mollicutes are difficult to grow in primary culture from host material and identification techniques are prolonged and involved, we are participating in a pilot study to evaluate the use of 16S rDNA sequence data as a rapid means of identifying a group of helical mollicutes (genus Spiroplasma). Sequence data on 10 Spiroplasma species, available from our earlier collaborative study on the phylogeny of these organisms, will be combined with DNA extraction and sequence analysis from another 40 currently defined Spiroplasma species to provide a comprehensive file to evaluate the practicality of this reference to provide rapid species identification. This activity is one part of a collaborative program to develop a multiple organism microbial identification project.